diff --git a/src/wp-content/themes/twentynineteen/style-editor.css b/src/wp-content/themes/twentynineteen/style-editor.css
index 3dd9c1eb8a..54487026e2 100644
--- a/src/wp-content/themes/twentynineteen/style-editor.css
+++ b/src/wp-content/themes/twentynineteen/style-editor.css
@@ -605,7 +605,7 @@ body .wp-block.aligncenter {
 }
 
 @media only screen and (min-width: 768px) {
-  body.block-editor-writing-flow,
+  body.block-editor-iframe__body, body.block-editor-writing-flow,
   body .block-editor-writing-flow {
     max-width: 80%;
     margin: 0 10%;
diff --git a/src/wp-content/themes/twentynineteen/style-editor.scss b/src/wp-content/themes/twentynineteen/style-editor.scss
index 2c129c809a..ce8a2883f8 100644
--- a/src/wp-content/themes/twentynineteen/style-editor.scss
+++ b/src/wp-content/themes/twentynineteen/style-editor.scss
@@ -36,6 +36,7 @@ body {
 
 	@include media(tablet) {
 
+		&.block-editor-iframe__body,
 		&.block-editor-writing-flow,
 		.block-editor-writing-flow {
 			max-width: 80%;